I've been having issues with the 3ph on my MF1655. It works strong until she is nice and warm. About a half hour of use,it won't pick up the implement. I've checked the fluid before and it's up. But tonight I thought I'd check it again. Have some work for it tomorrow. When I unscrewed the dipstick,there was a gush of air released. So my question is, is there a vent in the rear-end?